NEW
2019 Innovation Awards

Alternative overhead line tower preparation methods (high-pressure jetting)

Call
DNO-19-02
PLEASE NOTE: THE PRESENTATION DAY FOR THIS CALL HAS BEEN CHANGED TO 21/11/19

Background 
 
National Grid Electricity Transmission (NGET) operates around 22,000 overhead line towers on its network, and corrosion presents the most significant aging issue, although material loss can be minimized through application of an optimal painting regime. As part of current NGET maintenance practices, towers require painting at a frequency of approximately once every 18 years, meaning that on average each year more than 1,200 towers must be repainted at an annual cost of around £18M.

In the majority of cases, the current practice of tower preparation (and painting) is executed whilst live conductors are present on one side of the tower in question.

Current NGET policy dictates that high-pressure jetting may only be employed up to the height of the ‘bend line’ of the tower, below the height of the lower conductor. Above this height, preparation is limited to the use of wire brushing and anti-fungal treatments due to the risk of flashover.